Chez inc7: reader features — ##Inf/##NaN, #(...), #?(...), ns :require aliases

Reader gaps the Chez-hosted analyzer hit where the Janet reader didn't:
- ##Inf / ##-Inf / ##NaN symbolic literals (## dispatch -> flonum).
- #(...) anonymous fn shorthand -> (fn* [p__N#] body), with % / %N / %& and the
  max-positional arity rule; scans + rewrites list/vector/set/map bodies.
- #?(...) reader conditional: feature set {:jolt :default}, first matching clause
  wins. #?@ splicing not yet supported (one niche case allowlisted).
- (ns name (:require [a :as x])) — the require pre-scan now also reads aliases
  from an ns form's :require/:use clauses, not just bare (require ...).

Zero-Janet corpus parity 2240 -> 2288, 0 divergences (2 now-reachable cases
allowlisted: str of Infinity inside a collection — same as the prelude gate —
and #?@ splice). spine-test 35/35; prelude parity 2295 unchanged, 0 new
divergences.

test/chez/run-corpus-zero-janet.janet

@@ -69,7 +69,13 @@
     "direct builtin override" true
     "methods table inspectable" true
     "atom override fires nested" true
-    "atom?" true})
+    "atom?" true
+    # str of an Infinity/NaN INSIDE a collection renders the flonum form, not
+    # "Infinity" — the prelude gate allowlists this too (Phase-2 recursive str).
+    "inf inside coll" true
+    # #?@ reader-conditional splicing into the enclosing seq isn't supported yet
+    # (plain #? works); a single niche corpus case.
+    "reader cond splice" true})
 
 (var pass 0)
 (def crashes @[])      # nonzero chez exit (analyzer/emitter raised, or runtime gap)
@@ -157,7 +163,7 @@
 
 # Regression floor: raise as the Chez-hosted compiler closes gaps. The gate fails
 # on any NEW divergence or if pass drops below the floor. Strided runs scale to 0.
-(def base-floor (scan-number (or (os/getenv "JOLT_CHEZ_ZJ_FLOOR") "2240")))
+(def base-floor (scan-number (or (os/getenv "JOLT_CHEZ_ZJ_FLOOR") "2288")))
 (def floor (if (os/getenv "JOLT_CORPUS_LIMIT") 0 base-floor))
 (when (or (> (length diverged) 0) (< pass floor))
   (printf "REGRESSION: pass %d < floor %d or %d new divergence(s)" pass floor (length diverged)))